A guide wire is used to introduce and guide a catheter, for example, which is used in the treatment of a portion of the body on which it is difficult to perform surgery, in minimal invasive treatment for a human body, or in angiographic examination and treatment for heart disease, to a target portion.
When percutaneous coronary intervention (PCI) or the like is performed, a guide wire along with a balloon catheter is inserted into the front of a stenotic portion of a coronary artery, that is, a target portion, while a distal end of the guide wire protrudes further than a distal end of the balloon catheter, the distal end of the guide wire passes through the stenotic portion, a balloon of the balloon catheter is guided to the stenotic portion along the guide wire, and the balloon is inflated to open the stenotic portion, thereby allowing blood to flow.
In order for the guide wire to be able to be inserted from a femoral artery and move forward to the coronary artery via an aorta, an aortic arch, a coronary ostium or the like using a Seldinger technique, the guide wire is preferably good in flexibility (followability) required to track a blood vessel, pushing performance (pushability) by which a pushing force applied on a proximal portion is effectively transmitted to a distal end portion, and torque transmission performance by which a rotating force applied on a proximal end side of the guide wire is reliably transmitted to a distal end side of the guide wire.
In order to select an appropriate branch of a junction of the coronary artery or the like using the guide wire, and to move the guide wire forward, a distal end portion of the guide wire may be deformed to the shape of the junction. Typically, the deformation is performed by the fingers of a doctor or other personnel during an operation, and is referred to as reshaping.
In particular, when the distal end of the guide wire is inserted into a distal coronary artery, it is not possible to select a desired branch using a guide wire with a pre-formed angled or a J-shaped distal end as known in the art, and in many cases, the distal end of the guide wire is changed to the desired shape, and the guide wire is re-inserted. When the distal end of the guide wire is still not fitted to the desired shape, the guide wire has to be removed from the catheter, be re-shaped, and then be inserted. Accordingly, the distal end portion of the guide wire is required to have flexibility along with reshaping performance.
There is known in the art to have a flat portion of the distal end portion being formed in a plate shape so as to obtain flexibility of the distal end portion of the guide wire (for example, as shown in JP-A-2012-5722).
Since the flat portion of the guide wire disclosed in JP-A-2012-5722 is formed in a plate shape, it is possible to bend the flat portion in a thickness direction. That is, the flat portion has good flexibility. The flat portion has sufficient flexibility, however, in contrast, the plate-like flat portion has relatively low torsional rigidity. Accordingly, there is a problem in that torque transmission performance is not sufficient. Since the flat portion has sufficient flexibility but low torsional rigidity, when the guide wire is pushed toward the distal end side, the flat portion may buckle, which is a problem. In the guide wire in the related art, flexibility, torque transmission performance, and pushing performance have not been compatible with each other.